Rotary drying apparatus



March 31. 192%.

F. T. GRAVS ROTARY DRYING APPARA''US 2 Shouts-shbat' 1 Fil ed June a, 1921 Iz? Um zier' March 31. 1925.

F'. T. GREAVES RQTARY DRYNG APPARATUS Filed Juqq, 1921 2 Shouts-shoqi 2 Patented Mar. 31, 1925,

UNITED S-TATES PAT FBEDERICK T. GREAVES, O'F CEICAGO, IILINOIS ROTARY parme APPARATUS.

Application filed June 8, 1921. Serial No. &75,959.

To all whom z't may concern:

Be it known that `I, FREDERIK T.. GRnAVEs, a citizen of the United States, and a resident of Chicago, county ofCook, State of Illinois, have invented a certain new and useful Improvement in Rotary Drying Apparatus, of which the following is a. specification.

This invention relates to drying mpparatus of that kind in-which the materials to be dried are introduced into acylindric rotary structure through which heated air or gases or products of combustion to pass, usually through a flue extending longitudinally of the structure, so that the materials are tumbled about in the cylindric structure and dried in the'desired manner before being discharged therefrom, the process being practically continuous.

Generally stated, the object of the invention is to provide a novel and improved conare allowed structon of drying apparatus of the forego-g ing general character, having provisions for more satisfactorily supplying the cylindric rotary structure with the heated gases or products of 'combustion necessa for the drying of the materials, while the latter are tumbling about and gradually travelling hop through the structure. preferably from one` end thereof to the `ot er, .thereby to insure the desired drying of the materials in an efficicnt manner.

Another object isto provide an improved Construction and arrangement whereby the heat radiatng surface of ;the heat flue is increased, for any given length' of flue, without increasin the diameter thereof, and whereby the ue is materially stiffened or strengthened throughout its length, being formed with longitudinal fins or webs alternating with channels on the "outer surface of the flue.

It is also an object to provide certain details and features of construction and combinations tending to increase the general efficiency and the desirability of a rotary drying apparatus of this particular charac ter.

To the foregoing and' other useful ends the invention consists in matters hereinafte' set forth and claimed and shown in the accompanying drawings in which- Fgure 1 is a longtudinal section of a rotary drying apparatus embodying the prin ciples of the invention.

Figure'2 is an enlarged transverse section of the rotary cylinder and its flue on line 2-2`in Figure 1. v

Figure 3 is an enlarged section on line 3-3inFigureL Figure 4 is an enlarged section on line 4-4: in Figure 1. :AS thus illustrated, the invention com- -prses an outer horizontally disposed drum -of any suitable character, such as the cylinder 1, provided with ring like tracks 2 that travel on rollers 3 suitably supported by bearings 4: mounted on the base 5 of the machine. 'A cog ring 6 encircles the cylinder and is engaged by a pinion 7 which .is rotated by power communicated thereto from any suitablesource and in any suitable manner. At oneen'd the cylinder is tapered at 8 and-has arotary connection 9 with the intake 10 of the suction blower 11, which latter is mounted .upon the roof of the urnace 12, this fan or blower being of any suitable or desird form or Construction. A per' 13 having a spout 14 extending through the tapered porton 15 of the blower intake rovide's means for feeding the materials nto the dryer'. As shown, the interior of the dryer. cylinder 1 is with longitudnal ribs or fins 16 which carry the materials upward and then drop them. At its discharge end the cylinder 1 is pro-- vided with an outlet 17 and with radial wings or fins 18 that car the materials upward a distance. A de ector 19 is arranged in position to deflect the materials provided carried u ward by the radial wings or fins 18 into t e discharge spout or outlet 17. Thu while the materials are continuously eedng throu h the spout 14 into one end ofthe dryer, t eheated' and dried materials this end portion of the flue are provided with lateral intakes 23 which are tapered as shown toward the center of the flue, and' which open on' the sides of the cylinder 1, and which are thus constantly -in communication with the chamber 24 of the furnace; so that the hot gases and products of coming the operation of the dryer. The tapered intakes .23 act as funnels and keep the flue in' communication with the furnace, much more eflectively during the rotation of the flue, than would be the case if these intakes 23 were made straight- Hence a large volume of heatand products. of combustion s taken into' the fire, for any given size of drier. As the flue is open at its end 25, it

follows that the stron caused by the fan or b ower 11 draws the gases and roducts of combustion through the flue an into the interior of the cylinder 1, in one direction, and then back in the opposite direction between the outer surface of the flue and the inner surface of the cylinder, whereby the materials gradually travel lengthwise of the dryer in one direction whle the strong current of heated air and hot gas'es -or products of combustion are caused to travel through and over the materials in the opposite direction. In other words, as shown in Figure 1, the materials being dried gradually progress or' slowly travel toward the' right, while the heated gases travel toward the left in 1 of the dryer.

As a matter of further and special im provement, the tubular flue 20 is preferably constructed as shown more clearly in Figures 2 and 3, being composed of a plurality of trough-like sections 26 having their edges Secured together at 27, thus providing the flue with external longitudinal fins or webs the cylinder having channels between them. The .di-` ameter of the flue thus constructed is, of

course, the diameter of the circle which intersects the outer edges of said fins or webs, and with this construction it will be seen that theheat radiating surface of the flue is much greater than would bethe case if the walls of the flue werercylindrial and formed on the line of said circle. Thus the heat radiating surface of the flue is in creased, without increasing its diameter, in the sense that itsradiating surface is much greater than would be the .case if the flue were simply a perfect cylinder equal in diameter to the diameter of the circle which intersects the extreme outer edges of the fins or webs formedat 27 by the edges of'the difl'erent sections. Also, it will be seen that with this construction the radiating surface is greater than would be the case if the flue were cylindrical on the line of a circle int ersectng the bottom of i each section 26,

and had radial wings or fins thereon to radiate the heat. The channeled or fluted formation of the-heat flue 20, in the manner shown 'and described, tends also to stifen 'the 'flue', as the fins or webs which extend Parallel on -the outer surface thereof serve draft or suction v to materially stifl'en the tubular structure thus provided, permitting the use of thinner sheet metal. In the Construction of the flue in this way, any suitable or desired method can be employed, but as a matter of still further and special improvement 'the sec- 'tions 26 are preferably' formed by first rolling the sheet metal into cylinders, and by then dividing these 'cylinders longitudinally to form the trough-like sections., The sectons thus produced are then turned wrong-side out, thefeby to bring the channels into position to face outwardly, and the edge portions of the sections are tle riveted o'r welded or otherwise secured together, whereby two-ply sheet metal fins 01' webs are formed which not only readily structure -rotates about a horizontally dsposed axis to 'tumble the materials about therein. The heated air or gases 0l products of combustion are admitted through the sides of the cylindrical rotary structure, but are 'discharged axially from the end of the cylinder, through the 'tapered portions 8 and 15, and through the blower intake 10 which forms a reduced axial end-portion, for the cylinder. The materials and the heat are introduced into the structure at the same end of the' rotary cylinder, and the heat loaae with the moisture extract'ed from the materials is discharged from this same end while the thoroughly driecl materialsare at the same timebeing dscharged from the other end of the dryer. Also, it will be seen that the channels formed between the -fins or webs 27 of the flue enable the latter,

as it rotates, to Carry the materials Upward and over to the other side, as they fall from the carrying webs 16 previously mentioned whereby the materials may rest for amoment or two upon the flue, instead of instantly sliding of as would be the case if theflue had cylindrical side walls. -In effect the flue formed as shown and described is provided with hollowfins or webs, instead of having solid metal fins or webs or ribs, and thus the internal Capacity oral-ea of the flue is greate' than would be the case if it were cylindrical on` the line of a circle intersecting the bottom' of each troughshaped section 26, each hollow web or fin having a certain amount of space therein which contrbutes' to the total capacity, or cross-sectional area of the flue as a whole. With this Construction, moreover, practically every inch of outer surface of the flue is formed by a comparatively thin layer of sheet metal which is all'that is between the heated side. Air enters the drum through the `outlet 17' for the materials, and this air is heated and passes between 'the outer surface of the flue and the inner 'surface of the' `trough-like sections '26 ofthe flue and is absorbed by the materials and air outside the flue. Practicaly, 'therefor'e, as stated, it is true that wherever the materials make contact with the outer surface of the flue th'ey do so on a thin sheet metal wall the inner u surface of which is in direct contact with the gases and smoke and products of combustion taken from the furnace or other means for supplying the heat. .Thiwqd not be true, of course, if the longtudnal ribs or webs or fins provided on the flue ,were solid, or 'not hollow, because in such case the materials could make contact wth one surface of any fin or rib or wing and the opposite v surface of this wing or fin would be a part of the outer surface of the flue, instead of a part of the inner surface thereof. `Thus, as stated, the internal capacity or area of the flue is greater with the .construction shown and described, and the direct radiating; surface of the flue is greater than would be'the case if the flue were cylindrical on the line of a circle in tersecting the base or center portions or bottom of each trough-like section 26, wth merely straight radial wings or fins of sheet metal on the outer surface thereof, assuming that these straight wings. or fins were of such size that their outer edges terminated on the line of the circle (previously mentioned) intersecting the' outer edges 27 of the flue shown and described; for with the latter Construction as stated, the interier or space within the flue is practically extended outward into the two wings or fins themselves, thus providing hollow and internally heated wings or fins, instead of solid ribs or wings which would be dependent upon their points of attachment to the cylindrical flue for the transmission of heat to' their outer edges.

It will be seen that passages 23 are tapered inwardl'y, so that they are funnel shaped, with the wide mouth of each funnel presented in position to receive the heated products of combustion from the furnace. The 'drum rotates ata greater speed ases inside and the materials out-' than the flue, of: course, inasmuch as the' drum is of larger diameter than the flue, notwthstanding that they rotate in unison about a common axis, and hence the outer end of each passage 23 is advantageously larger than its inner end, in the manner shown and described. Furthermore, it will I vare more than foursections and the width of each channel thus `provided on the outer surfaceof the flue is 'approximately equal to one-half of the internal diameter of the flue, or at least less than said diameter. Moreover, it will be seen that the-flue is so supported in 'the drum that the materials can fall from the descending side of the flue to approximatelythe bottom of the drum as the materials will fall freely between the gaps provided between the wings or veins 16 and the outer edges of the flue; and, in addition, the structure thus provided affords free circulation of'the heate'd air and products of combustion around or circumferentially of the flue during the operation of the drying apparatus; and, it will be seen that this free circulation'of the gaseous elements circumferen'tially of the flue takes place before they pass between the inwardly tapered or funnel shaped passages 23, whereby very free circulation of both gases and the materials are ensured within the drum and around the outer surface of the heat flue. i

It will be seen that the materials slide down the shoot or spout 14 and enter the drum without having to pass by the intake of the fan before entering the drum. Thus there is less danger of the materials being sucked into the fan, and better results are ensured.- Furthermore, the tapered formation of the intake openings 23, as shown in Figure 2, tends to 'increase the period of time during which the intake of the flue 1 is in communication with thefurnace or other source of heat. The circumference of the drum 1, of course, travelsfaster than the structure of the flue, when the entire structure is rotated, and it follows that by outwardly flaring the intake openings 23 it is easier for the heat and products of combustion to. enter from 'the furnace, than would be the case if these openings 23 were i made' strai ht .or .with parallel sides, instead of with si es which' are radial as shown in Figure 2 of the drawings. The mner flue is so formed that it hasboth external an'd internal channelsthe external Channels being more or less U-shaped in cross section, while the internal channels are substantially V-shaped in cross section. The walls 26 of the flue, however, constitute the entire flue structure and thus the walls which are necessary to enclose the interor of the' flue '55 end of said drum, whereby draws o't thehot gases which have been.

constitute everything' that the flue involves in the`way of structure. The heating materials have free and unrestrained circulation circumferentially around the flue in ,fthe manner shown and described.

What I claim as my invention is- 1. A\ drying apparatus comprising a rotary drum for receving and tumbling about therein the materials to be dried, a flue extending longitudinally in said drum, suction e `means at one end of the drum. to draw the air therefrom, feeding means at the same endto introduce the materials into the drum, .said flue being 'externally and internally 1channeledf longitudinally thereof, .means r whereby said flue has a lateral intake on the side of said drum near said end thereof, and

instrumentalties for supplying heat to said 36 intake being formed by a plurality of incwardly tapered short assages extending outwardly from the si es of 'the flue and 'opening on the sides of the drum 'to communicate with said instrumentalities, each .passage having radial walls extending outward from the edges of the external channels of said'flue.

` 3. 'A structure as specified in claim 1, said drumbeing provided with an outlet for the 3 materials' and an inlet fon air at the other end thereof, whereby air ma-v enter and circulate freely circumferentiallyaround said flue.

4. A structure said instrumentalities comprising a furnace having a chamber to recevc the-hot gases and products of combustion and wherein rotates the portion of the drum having said' 'intake, whereby the furnace Supplies heated' gases which are free to circulate circumferentially around said flue.

5. A structure as specified in' claim 1, the suction means specified comrisin a blower having its intake conn'ecte axia y to the the blower free to circulate circumferentially around .said flue. e

6. In a drying apparatus, the combination of a 'plurality of trough shaped sections having their edges united to form an approximately cylindrical flue having'longitudjnal channels on the outer surface thereof, means whereby heated gases are caused to pass through said flue, and a rotary drum en- -each opening.

in said drum, comprising sheet metal secas specified 'in claim closing said flue and adapted. to receive the materals to be dried, with space between the drum and the flue to permit free circulation of the heat circumferentially around the channeled outer surface of said flue.

7 'A structure as specified `in claim 6, said flue being suitably Secured `to the drum to rotate therewith, and to aiford free circulation of the heat circumferentially around the outside of the flue.

8. A structure as specified in claim G, said flue having more than four of said sections and the width. of each channel bein less' than the internal diameter of said rum, being supported to rotate with said drum.

- 9. In a drying apparatus, a rotary drum having one or 'more funnel-shaped or inwardly tapered side openings cforming a lateral intake for heated gases to dry the ma terials, the ntake openings being thus tapered to increase the area of communication with the source of heat at the outer end of each opening, and means to introduce the materials to be dried in said drum.

10. In a drying apparatus, the combination of 'a furnace having a chamber to receive the heat andproducts of combustion, and a cylindric structure arranged to ro- 'tate in said chamber and having one or -more funnel-shaped or inwardlj tapered lateral intake openings to receive the; heated gases necessary for drying the materials in said dryer, the intake openings being thus tapered to .increase the area of communication with the source of heat at the o-uter end of i 11. In drying apparatus having a. rotary drum, a tubular heat fluetherefor, enclosed tionssecured toget er at their edges with their concave surfaces facing outward to provide external channelsextending longitudinally of the flue and alternating with arallel fins or webs where said edges are Secured together, there being more than four of said sections and the width of each channel being less than the internal diameter of said e 12. In a rotary dryer, the combination of a rotary drum in which the materials to be dried are received and tumbled about,`a flue for heated gases extending centrally and longitudinally through the interior of .said

drum, lateral heat intake means extending through said'. drum to said flue, and means to draw the hot gases out axially from the end of said drum, said flue being rigidly connected to said drum, so that the two rotate in`unison, 'without interferingwith the free circulation of the hot gases circumferentially of said flue, within the drum, said flue having means on its-enter surface adapted to catch and retain quantities of the materials dropped or thrown thereon by the rotation of the drum, and said means being presented to the free circulation of the hot gases around the flue.

13. In drying apparatus, a cyli'ndrcal flue for heated gases in the form of a tubular structure having longitudinal hollow wings or fins forming external Channels between them, so that the interior of the flue extends a distance into each wing or fin, the wings v being holle-w to a point near the outer edges .10

thereof, and the width of each channel being approximately equal to one-half of the internal diameter of the flue.

14. In drying apparatus, a flue for heate gases therefor in the form of a tubular structure having longitudinal wings or fins forming Channels between them, each wing or fin being hollow to permit the interior of the flue to extend to` a point near the outer edge thereof, and means to support the flue* in such a manner that the hot gases and materials have free circulation outside said flue circumferentially thereof.

15. In a rotary dryer, the combination of a rotary drum, and a flue for heated gases therein, said flue having an interior chamber, and having enclosing walls for said chamber which enclosng walls are .flush where they meet at their outer edges and constitute the entire structure of the-flue.

16.' In a rotary dryer, the combination of a rotary drum, and a flue for heated ases therein, said flue having external an internal longitudinal Channels, there being more than four relatively wide Channels outv side, and more than four r'elatively narrow Channels inside the flue.

17. In a rotary dryer, the combination of a ro-'tary drum, a flue for heated gases there in, a fan having an ntake to draw the hot gases through the flue andthen through the drum and means for' feeding materials into the end of the drum which communicates with said fan, said feeding means projecting into the end of the arm and being arranged to obviate the necessity of materials having to pass the fan intake before 'enter-` ing the drum.

' FREDERICK T. GREAVES. I 

